Resource allocation method for downlink transmission in a multicarrier-based CDMA communication system

Abstract

In a resource allocation method in a multicarrier-based mobile communication system that includes base stations and supports multiple access of a plurality of terminals identified using codes, the service area of each base station is divided into at least two virtual cells having different radii about the base station, and resources are actively allocated to terminals located in the service area according to distribution of the terminals in the virtual cells. The service area is divided into two virtual cells based on the received signal strengths of the terminals for a specific subchannel, and the specific subchannel is allocated to one terminal or at most two terminals according to distribution of the terminals in the virtual cells.

1 . A resource allocation method in a communication system supporting multiple access of a plurality of terminals identified using spreading codes, the method comprising: 
 collecting, from terminals located in a service area of a base station, information of respective received signal strengths of the terminals for channels;    determining whether a terminal having a received signal strength higher than a predetermined threshold for a specific subchannel is present; and    allocating the specific subchannel to at least one terminal as a function of the determination.    
   
   
       2 . The method according to  claim 1 , further comprising allocating the specific subchannel to a terminal having a highest received signal strength, among the terminals located in the service area of the base station if there is no terminal having a received signal strength higher than the predetermined threshold for the specific subchannel.  
   
   
       3 . The method according to  claim 1 , further comprising determining whether the number of terminals having a received signal strength higher than the predetermined threshold for the specific subchannel is greater than 1, if a terminal having a received signal strength higher than the predetermined threshold for the specific subchannel is present.  
   
   
       4 . The method according to  claim 3 , wherein if the number of terminal having a received signal strength higher than the predetermined threshold for the specific subchannel is 1, the specific subchannel is allocated to the terminal having the received signal strength higher than the predetermined threshold for the specific subchannel.  
   
   
       5 . The method according to  claim 3 , further comprising allocating the specific subchannel to a terminal having a highest received signal strength and a terminal having a second highest received signal strength among the terminals having a received signal strength higher than the predetermined threshold when the number of terminals having a received signal strength higher than the predetermined threshold for the specific subchannel is greater than 1.  
   
   
       6 . The method according to  claim 1 , further comprising: 
 allocating the specific subchannel to a terminal having a highest received signal strength among the terminals located in the service area of the base station when a terminal having a received signal strength higher than the predetermined threshold for the specific subchannel is not present,    allocating the specific subchannel to the terminal having the received signal strength higher than the predetermined threshold for the specific subchannel when one terminal having a received signal strength higher than the predetermined threshold for the specific subchannel is present, and allocating the specific subchannel to a terminal having a highest received signal strength and a terminal having a second highest received signal strength among two or more terminals having a received signal strength higher than the predetermined threshold if two or more terminals having a received signal strength higher than the predetermined threshold for the specific subchannel are present.    
   
   
       7 . The method according to  claim 6 , further comprising allocating the specific subchannel with maximum power to the terminal having the highest received signal strength, and the specific subchannel to the terminal having the second highest received signal strength, while gradually decreasing the maximum power allocated to the terminal having the highest received signal strength when two or more terminals having a received signal strength higher than the predetermined threshold for the specific subchannel are present.  
   
   
       8 . A resource allocation method in a multicarrier-based mobile communication system including base stations and supporting multiple access of a plurality of terminals identified using codes, the method comprising: 
 dividing a service area of each base station into at least two virtual cells having different radii about the base station; and    actively allocating resources to terminals located in the service area of the base station according to distribution of the terminals in the virtual cells.    
   
   
       9 . The method according to  claim 8 , wherein the radii of the virtual cells are determined based on received signal strength of the terminals for a specific subchannel.  
   
   
       10 . The method according to  claim 8 , wherein the radius of a first virtual cell is determined based on maximum transmission power of a specific channel, and the radius of a second virtual cell is previously determined based on a threshold transmission power less than the maximum transmission power.  
   
   
       11 . The method according to  claim 10 , wherein the distribution of the terminals is determined based on received signal strength of the terminals for the specific subchannel, the received signal strength being fed back from the terminals.  
   
   
       12 . The method according to  claim 11 , further comprising allocating the specific subchannel to a terminal having a highest received signal strength among the terminals in the first virtual cell if the terminals are all distributed in the first virtual cell.  
   
   
       13 . The method according to  claim 11 , further comprising allocating the specific subchannel to a terminal present in the second virtual cell if the terminals are distributed in both the first and second virtual cells.  
   
   
       14 . The method according to  claim 11 , further comprising allocating the specific subchannel to the terminal present in the second virtual cell if the terminals are distributed in both the first and second virtual cells and one terminal is present in the second virtual cell.  
   
   
       15 . The method according to  claim 11 , further comprising allocating the specific subchannel to a terminal having a highest received signal strength and a terminal having a second highest received signal strength of the specific subchannel among the two or more terminals present in the second virtual cell if the terminals are distributed in both the first and second virtual cells and two or more terminals are present in the second virtual cell.  
   
   
       16 . The method according to  claim 15 , further comprising allocating the specific subchannel with maximum power to the terminal having the highest received signal strength, and the specific subchannel is allocated to the terminal having the second highest received signal strength, while gradually decreasing the maximum power allocated to the terminal having the highest received signal strength and gradually increasing power for the terminal having the second highest received signal strength if two or more terminals are present in the second virtual cell.  
   
   
       17 . The method according to  claim 11 , further comprising: 
 allocating the specific subchannel to a terminal having a highest received signal strength among the terminals in the first virtual cell, if the terminals are all distributed in the first virtual cell,    allocating the specific subchannel to the terminal present in the second virtual cell if the terminals are distributed in both the first and second virtual cells and one terminal is present in the second virtual cell, and    allocating the specific subchannel to a terminal having a highest received signal strength and a terminal having a second highest received signal strength for the specific subchannel among the two or more terminals present in the second virtual cell if the terminals are distributed in both the first and second virtual cells and two or more terminals are present in the second virtual cell.    
   
   
       18 . The method according to  claim 17 , further comprising allocating the specific subchannel with maximum power to the terminal having the highest received signal strength, and the terminal having the second highest received signal strength, while gradually decreasing the maximum power allocated to the terminal having the highest received signal strength and gradually increasing the power for the terminal having the second highest received signal strength if two or more terminals are present in the second virtual cell.